Loans and Allowances for Credit Losses, Credit Quality Indicators (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	$ 4,378,265
Financing Receivable, Originated, 2019	3,248,779
Financing Receivable, Originated, 2018	2,818,040
Financing Receivable, Originated, 2017	1,914,647
Financing Receivable, Originated, 2016	1,454,082
Financing Receivable, Originated, 2015 or Prior	3,374,798
Financing Receivable, Revolving	6,582,767
Financing Receivable, Revolving, Converted to Term Loan	31,922
Total	23,803,300
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		$ 19,826,731
Non-Graded, Recorded Investment		1,924,256
Total	23,803,300	21,750,987
Related Allowance [Abstract]
Internally Risk Graded, Allowance		179,129
Non-Graded, Allowance		14,435
Total	419,777	210,759	$ 204,432	$ 202,534	$ 207,457
Commercial [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	1,103,310
Financing Receivable, Originated, 2019	1,654,628
Financing Receivable, Originated, 2018	1,544,785
Financing Receivable, Originated, 2017	1,073,379
Financing Receivable, Originated, 2016	787,890
Financing Receivable, Originated, 2015 or Prior	1,838,875
Financing Receivable, Revolving	5,559,326
Financing Receivable, Revolving, Converted to Term Loan	3,513
Total	13,565,706
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		13,997,538
Non-Graded, Recorded Investment		34,112
Total	13,565,706	14,031,650
Related Allowance [Abstract]
Internally Risk Graded, Allowance		117,236
Non-Graded, Allowance		951
Total	290,277	118,187	106,643	106,397	102,226
Commercial [Member] | Energy [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	59,186
Financing Receivable, Originated, 2019	65,464
Financing Receivable, Originated, 2018	109,513
Financing Receivable, Originated, 2017	7,959
Financing Receivable, Originated, 2016	15,537
Financing Receivable, Originated, 2015 or Prior	35,065
Financing Receivable, Revolving	3,424,377
Financing Receivable, Revolving, Converted to Term Loan	0
Total	3,717,101
Recorded Investment [Abstract]
Total	3,717,101	3,973,377
Commercial [Member] | Healthcare [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	356,834
Financing Receivable, Originated, 2019	650,054
Financing Receivable, Originated, 2018	626,935
Financing Receivable, Originated, 2017	433,280
Financing Receivable, Originated, 2016	241,595
Financing Receivable, Originated, 2015 or Prior	777,210
Financing Receivable, Revolving	239,882
Financing Receivable, Revolving, Converted to Term Loan	0
Total	3,325,790
Recorded Investment [Abstract]
Total	3,325,790	3,033,916
Commercial [Member] | Services [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	356,881
Financing Receivable, Originated, 2019	468,753
Financing Receivable, Originated, 2018	436,452
Financing Receivable, Originated, 2017	370,093
Financing Receivable, Originated, 2016	392,335
Financing Receivable, Originated, 2015 or Prior	785,357
Financing Receivable, Revolving	735,303
Financing Receivable, Revolving, Converted to Term Loan	651
Total	3,545,825
Recorded Investment [Abstract]
Total	3,545,825	3,122,163
Commercial [Member] | General business [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	330,409
Financing Receivable, Originated, 2019	470,357
Financing Receivable, Originated, 2018	371,885
Financing Receivable, Originated, 2017	262,047
Financing Receivable, Originated, 2016	138,423
Financing Receivable, Originated, 2015 or Prior	241,243
Financing Receivable, Revolving	1,159,764
Financing Receivable, Revolving, Converted to Term Loan	2,862
Total	2,976,990
Recorded Investment [Abstract]
Total	2,976,990
Commercial [Member] | Wholesale/retail [Member]
Recorded Investment [Abstract]
Total		1,760,866
Commercial [Member] | Manufacturing [Member]
Recorded Investment [Abstract]
Total		665,449
Commercial [Member] | Public finance [Member]
Recorded Investment [Abstract]
Total		709,868
Commercial [Member] | Other commercial and industrial [Member]
Recorded Investment [Abstract]
Total		766,011
Commercial real estate [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	578,864
Financing Receivable, Originated, 2019	1,192,717
Financing Receivable, Originated, 2018	1,022,093
Financing Receivable, Originated, 2017	534,721
Financing Receivable, Originated, 2016	357,066
Financing Receivable, Originated, 2015 or Prior	800,772
Financing Receivable, Revolving	207,467
Financing Receivable, Revolving, Converted to Term Loan	0
Total	4,693,700
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		4,433,783
Non-Graded, Recorded Investment		0
Total	4,693,700	4,433,783
Related Allowance [Abstract]
Internally Risk Graded, Allowance		51,805
Non-Graded, Allowance		0
Total	71,575	51,805	54,350	54,188	60,026
Commercial real estate [Member] | Residential construction and land development [Member]
Recorded Investment [Abstract]
Total		150,879
Commercial real estate [Member] | Retail [Member]
Recorded Investment [Abstract]
Total		775,521
Commercial real estate [Member] | Office [Member]
Recorded Investment [Abstract]
Total		928,379
Commercial real estate [Member] | Multifamily [Member]
Recorded Investment [Abstract]
Total		1,265,562
Commercial real estate [Member] | Industrial [Member]
Recorded Investment [Abstract]
Total		856,117
Commercial real estate [Member] | Other commercial real estate [Member]
Recorded Investment [Abstract]
Total		457,325
Paycheck Protection Program
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	2,097,325
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	0
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	2,097,325
Recorded Investment [Abstract]
Total	2,097,325
Related Allowance [Abstract]
Total	0
Loans to individuals [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	598,766
Financing Receivable, Originated, 2019	401,434
Financing Receivable, Originated, 2018	251,162
Financing Receivable, Originated, 2017	306,547
Financing Receivable, Originated, 2016	309,126
Financing Receivable, Originated, 2015 or Prior	735,151
Financing Receivable, Revolving	815,974
Financing Receivable, Revolving, Converted to Term Loan	28,409
Total	3,446,569
Recorded Investment [Abstract]
Total	3,446,569	2,084,172
Related Allowance [Abstract]
Total	57,925
Loans to individuals [Member] | Permanent Residential Mortgage [Member]
Recorded Investment [Abstract]
Total		1,057,321
Loans to individuals [Member] | Permanent Residential Mortgage [Member] | US Government Agency Insured Loans [Member]
Recorded Investment [Abstract]
Total		197,794
Loans to individuals [Member] | Home Equity Loan [Member]
Recorded Investment [Abstract]
Total		829,057
Loans to individuals [Member] | Residential mortgage [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	414,273
Financing Receivable, Originated, 2019	166,885
Financing Receivable, Originated, 2018	141,912
Financing Receivable, Originated, 2017	158,269
Financing Receivable, Originated, 2016	180,887
Financing Receivable, Originated, 2015 or Prior	415,582
Financing Receivable, Revolving	344,425
Financing Receivable, Revolving, Converted to Term Loan	26,911
Total	1,849,144
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		279,113
Non-Graded, Recorded Investment		1,805,059
Total	1,849,144	2,084,172
Related Allowance [Abstract]
Internally Risk Graded, Allowance		3,085
Non-Graded, Allowance		11,315
Total		14,400	15,534	15,724	17,964
Loans to individuals [Member] | Residential mortgage [Member] | US Government Agency Insured Loans [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	2,385
Financing Receivable, Originated, 2019	29,819
Financing Receivable, Originated, 2018	30,149
Financing Receivable, Originated, 2017	43,690
Financing Receivable, Originated, 2016	57,322
Financing Receivable, Originated, 2015 or Prior	220,882
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	384,247
Recorded Investment [Abstract]
Total	384,247
Loans to individuals [Member] | Personal [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	182,108
Financing Receivable, Originated, 2019	204,730
Financing Receivable, Originated, 2018	79,101
Financing Receivable, Originated, 2017	104,588
Financing Receivable, Originated, 2016	70,917
Financing Receivable, Originated, 2015 or Prior	98,687
Financing Receivable, Revolving	471,549
Financing Receivable, Revolving, Converted to Term Loan	1,498
Total	1,213,178
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,116,297
Non-Graded, Recorded Investment		85,085
Total	1,213,178	1,201,382
Related Allowance [Abstract]
Internally Risk Graded, Allowance		7,003
Non-Graded, Allowance		2,169
Total		9,172	10,150	9,388	9,473
Specific Allowance [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		19,826,731
Non-Graded, Recorded Investment		1,924,256
Total		21,750,987
Related Allowance [Abstract]
Internally Risk Graded, Allowance		179,129
Non-Graded, Allowance		14,435
Total		193,564
Nonspecific Allowance [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Non-Graded, Recorded Investment		0
Total		0
Related Allowance [Abstract]
Internally Risk Graded, Allowance		0
Non-Graded, Allowance		0
Total		17,195	$ 17,755	$ 16,837	$ 17,768
Performing [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		1,886,858
Performing [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		19,312,702
Performing [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		210,149
Performing [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		160,326
Performing [Member] | Commercial [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		34,075
Performing [Member] | Commercial [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		13,538,705
Performing [Member] | Commercial [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		187,881
Performing [Member] | Commercial [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		155,573
Performing [Member] | Commercial [Member] | Energy [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial [Member] | Energy [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	57,239
Financing Receivable, Originated, 2019	58,923
Financing Receivable, Originated, 2018	93,066
Financing Receivable, Originated, 2017	7,959
Financing Receivable, Originated, 2016	1,131
Financing Receivable, Originated, 2015 or Prior	6,716
Financing Receivable, Revolving	2,474,328
Financing Receivable, Revolving, Converted to Term Loan	0
Total	2,699,362
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		3,700,406
Performing [Member] | Commercial [Member] | Energy [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	0
Financing Receivable, Revolving	465,643
Financing Receivable, Revolving, Converted to Term Loan	0
Total	465,643
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		117,298
Performing [Member] | Commercial [Member] | Energy [Member] | Accruing Substandard [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	295
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	951
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	14,406
Financing Receivable, Originated, 2015 or Prior	0
Financing Receivable, Revolving	409,628
Financing Receivable, Revolving, Converted to Term Loan	0
Total	425,280
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		63,951
Performing [Member] | Commercial [Member] | Healthcare [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial [Member] | Healthcare [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	356,834
Financing Receivable, Originated, 2019	619,693
Financing Receivable, Originated, 2018	625,047
Financing Receivable, Originated, 2017	429,314
Financing Receivable, Originated, 2016	241,452
Financing Receivable, Originated, 2015 or Prior	749,439
Financing Receivable, Revolving	236,118
Financing Receivable, Revolving, Converted to Term Loan	0
Total	3,257,897
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		2,995,514
Performing [Member] | Commercial [Member] | Healthcare [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	27,500
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	3,019
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	13,393
Financing Receivable, Revolving	3,255
Financing Receivable, Revolving, Converted to Term Loan	0
Total	47,167
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		13,117
Performing [Member] | Commercial [Member] | Healthcare [Member] | Accruing Substandard [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	2,843
Financing Receivable, Originated, 2018	1,705
Financing Receivable, Originated, 2017	947
Financing Receivable, Originated, 2016	143
Financing Receivable, Originated, 2015 or Prior	11,443
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	17,081
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		20,805
Performing [Member] | Commercial [Member] | Services [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial [Member] | Services [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	356,443
Financing Receivable, Originated, 2019	445,488
Financing Receivable, Originated, 2018	406,761
Financing Receivable, Originated, 2017	345,936
Financing Receivable, Originated, 2016	380,205
Financing Receivable, Originated, 2015 or Prior	758,036
Financing Receivable, Revolving	689,917
Financing Receivable, Revolving, Converted to Term Loan	651
Total	3,383,437
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		3,050,946
Performing [Member] | Commercial [Member] | Services [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	344
Financing Receivable, Originated, 2019	11,778
Financing Receivable, Originated, 2018	1,734
Financing Receivable, Originated, 2017	597
Financing Receivable, Originated, 2016	8,415
Financing Receivable, Originated, 2015 or Prior	5,410
Financing Receivable, Revolving	10,043
Financing Receivable, Revolving, Converted to Term Loan	0
Total	38,321
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		29,943
Performing [Member] | Commercial [Member] | Services [Member] | Accruing Substandard [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	94
Financing Receivable, Originated, 2019	8,067
Financing Receivable, Originated, 2018	27,957
Financing Receivable, Originated, 2017	9,662
Financing Receivable, Originated, 2016	2,568
Financing Receivable, Originated, 2015 or Prior	15,185
Financing Receivable, Revolving	34,717
Financing Receivable, Revolving, Converted to Term Loan	0
Total	98,250
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		33,791
Performing [Member] | Commercial [Member] | General business [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	327,729
Financing Receivable, Originated, 2019	446,214
Financing Receivable, Originated, 2018	342,469
Financing Receivable, Originated, 2017	242,267
Financing Receivable, Originated, 2016	126,259
Financing Receivable, Originated, 2015 or Prior	229,142
Financing Receivable, Revolving	1,145,429
Financing Receivable, Revolving, Converted to Term Loan	2,766
Total	2,862,275
Performing [Member] | Commercial [Member] | General business [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	4,335
Financing Receivable, Originated, 2018	13,235
Financing Receivable, Originated, 2017	7,126
Financing Receivable, Originated, 2016	3,876
Financing Receivable, Originated, 2015 or Prior	3,457
Financing Receivable, Revolving	4,782
Financing Receivable, Revolving, Converted to Term Loan	21
Total	36,832
Performing [Member] | Commercial [Member] | General business [Member] | Accruing Substandard [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	1,005
Financing Receivable, Originated, 2019	15,955
Financing Receivable, Originated, 2018	11,316
Financing Receivable, Originated, 2017	11,007
Financing Receivable, Originated, 2016	7,501
Financing Receivable, Originated, 2015 or Prior	8,526
Financing Receivable, Revolving	8,894
Financing Receivable, Revolving, Converted to Term Loan	4
Total	64,208
Performing [Member] | Commercial [Member] | Wholesale/retail [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial [Member] | Wholesale/retail [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,749,023
Performing [Member] | Commercial [Member] | Wholesale/retail [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		5,281
Performing [Member] | Commercial [Member] | Wholesale/retail [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		5,399
Performing [Member] | Commercial [Member] | Manufacturing [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial [Member] | Manufacturing [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		623,219
Performing [Member] | Commercial [Member] | Manufacturing [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		18,214
Performing [Member] | Commercial [Member] | Manufacturing [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		13,883
Performing [Member] | Commercial [Member] | Public finance [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial [Member] | Public finance [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		709,868
Performing [Member] | Commercial [Member] | Public finance [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Commercial [Member] | Public finance [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Commercial [Member] | Other commercial and industrial [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		34,075
Performing [Member] | Commercial [Member] | Other commercial and industrial [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		709,729
Performing [Member] | Commercial [Member] | Other commercial and industrial [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		4,028
Performing [Member] | Commercial [Member] | Other commercial and industrial [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		17,744
Performing [Member] | Commercial real estate [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial real estate [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	578,864
Financing Receivable, Originated, 2019	1,184,368
Financing Receivable, Originated, 2018	1,021,832
Financing Receivable, Originated, 2017	517,976
Financing Receivable, Originated, 2016	347,920
Financing Receivable, Originated, 2015 or Prior	780,900
Financing Receivable, Revolving	207,440
Financing Receivable, Revolving, Converted to Term Loan	0
Total	4,639,300
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		4,381,663
Performing [Member] | Commercial real estate [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	261
Financing Receivable, Originated, 2017	12,326
Financing Receivable, Originated, 2016	2,571
Financing Receivable, Originated, 2015 or Prior	8,903
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	24,061
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		22,145
Performing [Member] | Commercial real estate [Member] | Accruing Substandard [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	8,349
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	4,187
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	4,824
Financing Receivable, Revolving	27
Financing Receivable, Revolving, Converted to Term Loan	0
Total	17,387
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		2,349
Performing [Member] | Commercial real estate [Member] | Residential construction and land development [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial real estate [Member] | Residential construction and land development [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		150,529
Performing [Member] | Commercial real estate [Member] | Residential construction and land development [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Commercial real estate [Member] | Residential construction and land development [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Commercial real estate [Member] | Retail [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial real estate [Member] | Retail [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		743,343
Performing [Member] | Commercial real estate [Member] | Retail [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		12,067
Performing [Member] | Commercial real estate [Member] | Retail [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,243
Performing [Member] | Commercial real estate [Member] | Office [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial real estate [Member] | Office [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		923,202
Performing [Member] | Commercial real estate [Member] | Office [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		5,177
Performing [Member] | Commercial real estate [Member] | Office [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Commercial real estate [Member] | Multifamily [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial real estate [Member] | Multifamily [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,257,005
Performing [Member] | Commercial real estate [Member] | Multifamily [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,604
Performing [Member] | Commercial real estate [Member] | Multifamily [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		95
Performing [Member] | Commercial real estate [Member] | Industrial [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial real estate [Member] | Industrial [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		852,539
Performing [Member] | Commercial real estate [Member] | Industrial [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,658
Performing [Member] | Commercial real estate [Member] | Industrial [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,011
Performing [Member] | Commercial real estate [Member] | Other commercial real estate [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial real estate [Member] | Other commercial real estate [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		455,045
Performing [Member] | Commercial real estate [Member] | Other commercial real estate [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,639
Performing [Member] | Commercial real estate [Member] | Other commercial real estate [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Paycheck Protection Program | Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	2,097,325
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	0
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	2,097,325
Performing [Member] | Loans to individuals [Member] | Permanent Residential Mortgage [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		758,260
Performing [Member] | Loans to individuals [Member] | Permanent Residential Mortgage [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		276,138
Performing [Member] | Loans to individuals [Member] | Permanent Residential Mortgage [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		78
Performing [Member] | Loans to individuals [Member] | Permanent Residential Mortgage [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		2,404
Performing [Member] | Loans to individuals [Member] | Permanent Residential Mortgage [Member] | US Government Agency Insured Loans [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		191,694
Performing [Member] | Loans to individuals [Member] | Permanent Residential Mortgage [Member] | US Government Agency Insured Loans [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Loans to individuals [Member] | Permanent Residential Mortgage [Member] | US Government Agency Insured Loans [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Loans to individuals [Member] | Permanent Residential Mortgage [Member] | US Government Agency Insured Loans [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Loans to individuals [Member] | Home Equity Loan [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		817,976
Performing [Member] | Loans to individuals [Member] | Home Equity Loan [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Loans to individuals [Member] | Home Equity Loan [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Loans to individuals [Member] | Home Equity Loan [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Loans to individuals [Member] | Residential mortgage [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		1,767,930
Performing [Member] | Loans to individuals [Member] | Residential mortgage [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	414,273
Financing Receivable, Originated, 2019	166,795
Financing Receivable, Originated, 2018	138,524
Financing Receivable, Originated, 2017	157,514
Financing Receivable, Originated, 2016	178,830
Financing Receivable, Originated, 2015 or Prior	390,803
Financing Receivable, Revolving	341,673
Financing Receivable, Revolving, Converted to Term Loan	26,129
Total	1,814,541
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		276,138
Performing [Member] | Loans to individuals [Member] | Residential mortgage [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	47
Financing Receivable, Originated, 2018	1,879
Financing Receivable, Originated, 2017	20
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	309
Financing Receivable, Revolving	527
Financing Receivable, Revolving, Converted to Term Loan	12
Total	2,794
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		78
Performing [Member] | Loans to individuals [Member] | Residential mortgage [Member] | Accruing Substandard [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	39
Financing Receivable, Revolving	159
Financing Receivable, Revolving, Converted to Term Loan	12
Total	210
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		2,404
Performing [Member] | Loans to individuals [Member] | Residential mortgage [Member] | US Government Agency Insured Loans [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	2,385
Financing Receivable, Originated, 2019	29,819
Financing Receivable, Originated, 2018	29,745
Financing Receivable, Originated, 2017	43,690
Financing Receivable, Originated, 2016	57,322
Financing Receivable, Originated, 2015 or Prior	214,889
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	377,850
Performing [Member] | Loans to individuals [Member] | Personal [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		84,853
Performing [Member] | Loans to individuals [Member] | Personal [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	182,066
Financing Receivable, Originated, 2019	204,478
Financing Receivable, Originated, 2018	79,041
Financing Receivable, Originated, 2017	104,217
Financing Receivable, Originated, 2016	70,812
Financing Receivable, Originated, 2015 or Prior	98,598
Financing Receivable, Revolving	471,503
Financing Receivable, Revolving, Converted to Term Loan	1,498
Total	1,212,213
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,116,196
Performing [Member] | Loans to individuals [Member] | Personal [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	42
Financing Receivable, Originated, 2019	24
Financing Receivable, Originated, 2018	11
Financing Receivable, Originated, 2017	53
Financing Receivable, Originated, 2016	46
Financing Receivable, Originated, 2015 or Prior	45
Financing Receivable, Revolving	1
Financing Receivable, Revolving, Converted to Term Loan	0
Total	222
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		45
Performing [Member] | Loans to individuals [Member] | Personal [Member] | Accruing Substandard [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	211
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	265
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	0
Financing Receivable, Revolving	15
Financing Receivable, Revolving, Converted to Term Loan	0
Total	491
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		143,554
Non-Graded, Recorded Investment		37,398
Nonperforming Financial Instruments [Member] | Commercial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		115,379
Non-Graded, Recorded Investment		37
Nonperforming Financial Instruments [Member] | Commercial [Member] | Energy [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		91,722
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial [Member] | Energy [Member] | Nonaccruing substandard and doubtful [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	1,652
Financing Receivable, Originated, 2019	6,541
Financing Receivable, Originated, 2018	15,496
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	28,349
Financing Receivable, Revolving	74,778
Financing Receivable, Revolving, Converted to Term Loan	0
Total	126,816
Nonperforming Financial Instruments [Member] | Commercial [Member] | Healthcare [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		4,480
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial [Member] | Healthcare [Member] | Nonaccruing substandard and doubtful [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	18
Financing Receivable, Originated, 2018	183
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	2,935
Financing Receivable, Revolving	509
Financing Receivable, Revolving, Converted to Term Loan	0
Total	3,645
Nonperforming Financial Instruments [Member] | Commercial [Member] | Services [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		7,483
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial [Member] | Services [Member] | Nonaccruing substandard and doubtful [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	3,420
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	13,898
Financing Receivable, Originated, 2016	1,147
Financing Receivable, Originated, 2015 or Prior	6,726
Financing Receivable, Revolving	626
Financing Receivable, Revolving, Converted to Term Loan	0
Total	25,817
Nonperforming Financial Instruments [Member] | Commercial [Member] | General business [Member] | Nonaccruing substandard and doubtful [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	1,675
Financing Receivable, Originated, 2019	3,853
Financing Receivable, Originated, 2018	4,865
Financing Receivable, Originated, 2017	1,647
Financing Receivable, Originated, 2016	787
Financing Receivable, Originated, 2015 or Prior	118
Financing Receivable, Revolving	659
Financing Receivable, Revolving, Converted to Term Loan	71
Total	13,675
Nonperforming Financial Instruments [Member] | Commercial [Member] | Wholesale/retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,163
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial [Member] | Manufacturing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		10,133
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial [Member] | Public finance [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial [Member] | Other commercial and industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		398
Non-Graded, Recorded Investment		37
Nonperforming Financial Instruments [Member] | Commercial real estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		27,626
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial real estate [Member] | Nonaccruing substandard and doubtful [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	232
Financing Receivable, Originated, 2016	6,575
Financing Receivable, Originated, 2015 or Prior	6,145
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	12,952
Nonperforming Financial Instruments [Member] | Commercial real estate [Member] | Residential construction and land development [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		350
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial real estate [Member] | Retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		18,868
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial real estate [Member] | Office [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial real estate [Member] | Multifamily [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		6,858
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial real estate [Member] | Industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		909
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial real estate [Member] | Other commercial real estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		641
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Loans to individuals [Member] | Permanent Residential Mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		493
Non-Graded, Recorded Investment		19,948
Nonperforming Financial Instruments [Member] | Loans to individuals [Member] | Permanent Residential Mortgage [Member] | US Government Agency Insured Loans [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Non-Graded, Recorded Investment		6,100
Nonperforming Financial Instruments [Member] | Loans to individuals [Member] | Home Equity Loan [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Non-Graded, Recorded Investment		11,081
Nonperforming Financial Instruments [Member] | Loans to individuals [Member] | Residential mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		493
Non-Graded, Recorded Investment		37,129
Nonperforming Financial Instruments [Member] | Loans to individuals [Member] | Residential mortgage [Member] | Nonaccruing substandard and doubtful [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	43
Financing Receivable, Originated, 2018	1,509
Financing Receivable, Originated, 2017	735
Financing Receivable, Originated, 2016	2,057
Financing Receivable, Originated, 2015 or Prior	24,431
Financing Receivable, Revolving	2,066
Financing Receivable, Revolving, Converted to Term Loan	758
Total	31,599
Nonperforming Financial Instruments [Member] | Loans to individuals [Member] | Residential mortgage [Member] | US Government Agency Insured Loans [Member] | Nonaccruing substandard and doubtful [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	404
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	5,993
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	6,397
Nonperforming Financial Instruments [Member] | Loans to individuals [Member] | Personal [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		56
Non-Graded, Recorded Investment		$ 232
Nonperforming Financial Instruments [Member] | Loans to individuals [Member] | Personal [Member] | Nonaccruing substandard and doubtful [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	17
Financing Receivable, Originated, 2018	49
Financing Receivable, Originated, 2017	53
Financing Receivable, Originated, 2016	59
Financing Receivable, Originated, 2015 or Prior	44
Financing Receivable, Revolving	30
Financing Receivable, Revolving, Converted to Term Loan	0
Total	$ 252